New Formulations of Fungicide May Alter Sensory Characteristics in White Wine

Fungicides are frequently used in viticulture to treat and prevent various diseases such grey mould (Botrytis cinerea), powdery mildew (Erisiphe necator), and downy mildew (Plasmopara viticola).  New formulations of fungicides are currently being tested to replace older, more controversial applications, which may provide similar if not better protection than the older methods.  Active ingredients considered in the new formulations include benalaxyl, benalaxyl-M, boscalid, cyazofamid, famoxadone, fenamidone, fluquinconazole, iprovalicarb, metrafenone, proquinazid, pyraclostrobin, trifloxystrobin, valifenalate, and zoxmide.

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After application of the fungicide, the residues are able to seep across the skin of the grape which can pass through the winemaking process and potentially alter the quality of the final wine.  Some research has shown that fungicide residues are responsible for slowly down or stopping alcoholic fermentation all together, which was found to be due to negative effects on the yeast and bacteria used in the process.  Other research has shown that these negative effects on alcoholic fermentation of grapes exposed to fungicide treatment can alter the chemical components of the wine, thus altering the phenolic composition and sensory characteristics.

The study presented today sought to examine the influence of new formulations of fungicides on the synthesis of volatile compounds in wine, as well as the sensory characteristics and overall quality.

Methods

The experiments performed for this study were field trials located in Ribadavia, in Galicia, northwest Spain (2009 vintage) at a vineyard producing white grapes (Vitis vinifera Godello cv). The vineyard plot was 2000m2, which was divided into 12 rows with 35-40 vines per row.  Vines were spaced 1m apart, with 1.8m between rows.  Vines were 10 years old and were trained on a double cordon trellis.  Different treatments were applied to control for downy mildew, powdery mildew, and grey mould.  Rows were divided randomly into four plots (A, B, C, and D).  Then, different phytosanitary treatments were carried out in each plot.  9 applications were performed, at different phenological stages, using a M-83-E hand-gun sprayer.

For downy mildew, the following treatments were used:

·         Cabrio Top (55% metiram + 5% pyraclostrobin) and Fobeci (35% folpet + 6% benalaxyl + 3.2% cymoxanil) (applied in May)

·         Mandipropamid was applied as an active substance in plot A.

·         IR-5885 (6% valifenalate + 60% mancozeb) was applied in plot B.

·         Mildicut (2.5% cyazofamid) and Equation Pro (22.5% famoxadone + 30% cymoxanil) were applied to plots C and D, respectively.

·         The last application of all treatments was 3 days before harvest

·         Rows 11 and 12 were left untreated during the final application to serve as the control.

For powdery mildew and grey mould:

·         5 applications for powdery mildew treatment :

·         Talendo (20% proquinazid) was applied to plots A and D.

·         Vivando (50% metrafenone) was applied to plots B and C.

·         2 treatments for grey mould, 1 application each:

·         Cantus (50% boscalid) was applied to all plots.

·         Switch (37.5% cyprodinil + 25% fludioxonil) was applied to all plots.

Grapes were harvested in September, and at least 15 randomly selected bunch samples from each plot were used for analysis.

Single vinifications were performed, and there were no repetitions/replications.  Standard vinification techniques were used (I can provide details if you need them: just ask!).

After bottling, the following parameters were measured: pH, alcoholic degree, total maximum real acidity, total maximum sulfur.

Fungicide residues were measured using solid phase extraction clean-up, and by gas chromatography analysis.

Wines were tested in a sensory analysis for quality (color, aroma, taste, and mouth feel) by 7 trained/experienced panelists from the Valdeorras appellation in Spain.

Results

Fungicide Residues in Grape Samples after Harvest

            Control of Downy Mildew:

  • ¬† ¬† ¬† Residues of benalaxyl, cymoxanil, folpet, and pyraclostrobin were not detected in grapes, except for plot D (which had later applications of Equation Pro).
  • ¬† ¬† ¬† Applications of mandipropamid in plot A showed residual concentrations in grapes that was lower than maximum levels allowed established by the European Union.
  • ¬† ¬† ¬† Applications of mandipropamid in plots B, C, and D showed residual concentrations in grapes that was higher than maximum levels allowed established by the European Union.
  • ¬† ¬† ¬† Applications of IR-5885 in plot B showed residual concentrations of valifenalate in grapes that was higher than maximum levels allowed established by the European Union.
  • ¬† ¬† ¬† Applications of Mildicut in plot C showed residual concentrations of cyazofamid in grapes that was higher than maximum levels allowed established by the European Union.
  • ¬† ¬† ¬† Applications of Equation Pro in plot D showed residual concentrations of cymoxanil and famoxadone in grapes that was above and close to the maximum levels allowed established by the European Union.

Control of Powdery Mildew:

  • ¬† ¬† ¬† Applications of both Talendo and Vivando in all plots showed residual concentrations of proquinazid and metrafenone in grapes that was below the maximum levels allowed established by the European Union.

Control of Grey Mould:

  • ¬† ¬† ¬† Applications of both Cantus and Switch in all plots showed residual concentrations of boscalid in grapes that was below the maximum levels allowed established by the European Union.

Dissipation after Winemaking?

  • ¬† ¬† ¬† After the white winemaking process, there was a high (90%-99%) ¬†dissipation of fungicide residues initially detected, with the exception of valifenalate, which only had 32% dissipation.¬†

Sensory Analysis

  • ¬† ¬† ¬† 6 sensory attributes were significantly different between the wines created by grapes treated with different fungicide treatments and the control:

o   Odor intensity, apricot and floral odors, and flavor intensity were lower in wine A (from plot A) than the control.

o   Apricot and floral odors were lower in wine B (from plot B) than the control.

o   Color and odor intensity were higher, and apricot and floral odors were lower in wines C and D (from plots C and D) than the control.

o   The acidity from wine C was higher than wine D, with the control wine acidity falling in between the two.

  • ¬† ¬† ¬† Summary of results after many statistical analysis and tests:

o   There was a predominance of floral odors (with a distinct apricot odor) in wines made from grapes treated with downy mildew fungicides.

o   Quality was related to the balance of odors, and acidity levels.

o   Odor fineness was negatively correlated with a bitter taste.

o   Limpidness was positively associated with melon notes.

o   Viscosity was associated with tropical and Mediterranean fruit odors.

o   Odor intensity and persistent flavors were associated with citrus and herbaceous odors.

o   Bitterness was associated with green apple odors.

o   Overall quality was associated with dryness, smoothness, acidity and fruit tastes, and flavor intensity.

o   In summary, higher levels of fungicide residues result in higher color shades, higher tropical fruit odors, and higher sweet tastes.

In Summary

The new fungicide formulas tested resulted in fungicide residues in grapes that were close to or higher than levels currently allowed by the European Union.  Even though the majority of these fungicides dissipated after the white winemaking process, the exposure was ample enough to alter the flavor characteristics of the final wine. 

One problem I have with the result is that there was only one wine made per plot (no replication).  It is not completely clear if the results found were because of any particular fungicide treatment, or because of a difference in that particular batch of winemaking.  I’d like to see more replication by these and other authors, to be completely certain of the results.

It was also not clear to me whether the finished wines were poorer in quality than the controls, or if they simply just tasted different.  Different taste doesn’t necessarily mean poorer quality, so I am hesitant to draw any conclusions as to which fungicide treatment would be the best option.

What do you think of the results?  Are you seeing something in these results that I missed?  Feel free to leave any comments below.

Source: Gonz√°lez √Ālvarez, M., Noguerol-Pato, R., Gonz√°lez-Barreiro, C., Cancho-Grande, B., and Simal-G√°ndara, J. 2012. Changes in the sensorial attributes of white wines with the application of new anti-mildew fungicides under critical agricultural practices. Food Chemistry 130: 139-146.

DOI: 10.1016/j.foodchem.2011.07.018



I am not a health professional, nor do I pretend to be. Please consult your doctor before altering your alcohol consumption habits. Do not consume alcohol if you are under the age of 21. Do not drink and drive. Enjoy responsibly!

19 comments for “New Formulations of Fungicide May Alter Sensory Characteristics in White Wine

  1. Robert C
    September 15, 2012 at 9:48 am

    Not that I would want anyone to try it but does the fungicides themselves have an oder or taste? If there are, do they dissipate after the winemaking process?

    • Becca
      September 15, 2012 at 9:52 am

      Thanks for reading and commenting, Robert!

      Great question about the odor/taste of fungicides. I’m not 100% certain if they have a noticeable smell when sprayed (any vineyard managers/workers out there want to chime in on this???), but chemically they are present in the grapes at harvest. According to this study, these residual fungicide chemicals are dissipated throughout the winemaking process, but it appears as though they had undergone chemical reactions with sensory phenolics at some point to alter the flavor/aroma of the finished wine slightly (according to this study, more tropical and sweeter fruit tones).

  2. Jeffrey M
    September 15, 2012 at 9:48 am

    This looks like a good start to a long term study but I am quite hesitant to really look at it with any significance. No replication, very small sample size, and only one year of study. The title is misleading considering the data pool.

    • Becca
      September 15, 2012 at 9:52 am

      Hi Jeffrey,

      Thanks for your comments! I completely agree about being hesitant to draw any particular conclusions due to no replication, as I stated toward the end of my write-up.

      Good point about the title–I should have included the word “may” in there. “New Formulations of Fungicide MAY Alter Sensory Characteristics of White Wine”. In fact, I will change it, since that we’re not certain that it does in fact change these characteristics in all white wines with any consistency.

      Thank you for keeping me in check ;)

  3. Keith
    September 15, 2012 at 9:48 am

    Who is going to spray these within 3 days of harvest? Not exactly a real world spray situation. I suppose the boscalid for the grey mold could be sprayed then. But it was said to sprayed on all plots , I suppose even the control. Not very well done experiment at all.

    • Becca
      September 15, 2012 at 9:52 am

      Thanks for commenting, Keith. You’re right, spraying 3 days before harvest is a little crazy. I’m not certain why the authors choose to do that…”for the heck of it” is all that comes to mind at the moment.

      I guess from a purely scientific perspective, it’s interesting to note (sort of) that fungicides may alter wine flavor/aroma when sprayed so close to harvest, but when no one actually does that in reality, makes one wonder what the real point of the article was.

      Hopefully, this article will spur other scientists to question these methods/results, and perform new experiments with more widely used protocols to determine if this result will hold up or not.

  4. Robin
    September 15, 2012 at 9:48 am

    I agree with Keith above — who would spray 3 days before harvest? The PHI for each of these fungicides wasn’t mentioned in this article.

    • Becca
      September 15, 2012 at 9:53 am

      Thanks for your comments, Robin! I’m not certain why they chose to spray 3 days before harvest, but then again, I’m not sure the authors did a bunch of things ;) I read through the methods of the original paper, and to be honest, it’s written almost cryptic-like and is very hard to follow. I tried to find exact PHI information, but it isn’t really there in great detail.

      The only thing I could find was that for downy mildew, applications were first applied in May, then later applied to different plots. That’s it…”later”…hmmmm….they said the last application was Sept 18 (then the Sept 21st, 3 days before harvest app), but it wasn’t clear to me if they did anything in between. One thing they mentioned that I’m not sure about (since I’m not a vineyard lingo pro) was that these applications were performed “under critical agricultural practices without obeying the preharvest interval”.

      For powdery mildew and grey mould, they say that applications were performed under “good agricultural practices” with some applications from June 13 to 18, and others on June 19th.

      Hopefully this clears things up a little bit, but I’m still a little fuzzy on it.

      As I mentioned to Keith, hopefully someone will see this study and improve on it to determine what actually happens under typical vineyard management practices.

  5. WineKnurd
    September 15, 2012 at 9:49 am

    I spoke with a winemaker friend of mine and he said that the fungal sprays he has used have at least a 7 day “spray before harvest” requirement. he also says he can “taste” the chemicals in barrel samples, but this probably means he can taste the difference in such wines after fermentation, not the actual chemicals used.

    • Becca
      September 15, 2012 at 9:53 am

      Mmmmmm taste the chemicals….. ;)

      That’s interesting that he could taste a difference with a 7 day before harvest spray. Now I’m really curious if the results of this study can actually be replicated, and if the results hold true with earlier sprays, such as the one your friend described.

  6. Stan
    September 15, 2012 at 9:49 am

    I read the origincal paper from Food Chemistry. The fungicides applied 3 day before harvest have between a 7 to 35 day pre-harvest interval. In treatment E “the control” they respected the law and made no applications in violation of the label requirements. Residues over the EU limit AND changes in the wine detectable by the tasting panel were only in the treatments where they violated the pre-harvest limits.

    • Becca
      September 15, 2012 at 9:53 am

      Hi Stan,

      Perfect! Thanks for clearing up the PHI interval question for us. That’s one downside to presenting papers from all areas of science is that I’m bound to not see something! I’m happy you spotted it, and were able to share that with us.

  7. WineKnurd
    September 15, 2012 at 9:49 am

    Hey Becca, I did not mean that he could taste the chemicals after the 7 day spray, but could taste the difference in the wines between years with heavy use and years of lighter use. But ultimately the last spray is at least 7 days from harvest.

    • Becca
      September 15, 2012 at 9:53 am

      Oh, I figured that…I was just being silly :) The image popped into my head after I read your post, and I figured I’d write it for laughs!

      • WineKnurd
        September 15, 2012 at 9:54 am

        I get cassis, oak, and a subtle hint of fungicide- quite complex :)

  8. VineyardManager01
    September 15, 2012 at 9:50 am

    Anyone study the effects of these ‘chemicals’ on humans? As in ingesting? Most have restrictions on breathing and MSDS sheets with lots of warnings for workers. But OK to ingest. Why not just add them to the wine to get the taste you want?

  9. Monello
    September 15, 2012 at 9:50 am

    Wine grapes should not be grown for mass-consumption in areas where these poisons are required. It is that simple.

  10. WineKnurd
    September 15, 2012 at 9:50 am

    Remember that Copper Sulfate is allowed to be used in organic farming because it is “natural”, copper sulfate is in fact found naturally in the earth. But that doesn’t mean that there aren’t any effects on health or the environment. The synthetic fungicides are “one-and-done” applications, and the theory is that they are metabolized in the plant and no longer at harmful levels if the required grace period is allowed to expire before harvest. Maybe this is the reason why they researchers only waited 3 days after application, to provide a baseline for sensory comparisons since they knew that the chemicals would still be present.

  11. Fungicides
    September 15, 2012 at 9:50 am

    Wooowww…nice share and good informative content,tanks

Comments are closed.